CLINICAL CORE The Penn PET Addiction Center of Excellence (PACE) will provide the infrastructure and resources needed to promote PET neuroimaging studies by investigators currently conducting funded clinical addiction research at the Penn and Yale Schools of Medicine. The Clinical Core will provide the clinical services required to conduct planned pilot projects and subsequent projects identified beginning in year two of the P30 grant period. The Clinical Core will leverage existing clinical research resources at the Center for Studies of Addiction, a well- established center at the PSOM, other clinical resources in Philadelphia, and those in New Haven, CT. The Clinical Core will provide specialized expertise in the recruitment and assessment of patients with opioid use disorder (OUD) and healthy control subjects (HCs). To recruit participants with OUD, the Clinical Core will collaborate with two nearby residential addiction treatment programs, the Kirkbride Center and Snyder House, in which patients are detoxified and maintained drug free for up to three months. These programs are near the Penn campus in Philadelphia, which ensures that patients can easily be transported to the PET facilities for imaging. The Clinical Neuroscience Research Unit at the Connecticut Mental Health Center will serve a similar purpose for OUD patients at Yale. The Clinical Core will also recruit, screen, and evaluate a sample of opioid- exposed HCs who will be matched to the OUD subjects on key variables. Using a core battery of assessments, to which project-specific assessments and procedures will be added, the Clinical Core will promote the joint analysis of findings across the pilot projects and enable investigators to compare HCs who undergo imaging using more than one PET ligand. The Clinical Core will also manage the clinical data and their integration with those obtained by the Imaging Core to ensure the efficient generation of study findings and access to the data repository by investigators in the scientific community locally, regionally, and nationally. These activities will streamline recruitment, the evaluation of eligibility, the collection of research data, and the seamless integration of clinical and imaging activities for all pilot projects proposed in the Center. Finally, the Clinical Core will provide regulatory assistance to pilot project investigators to ensure compliance with all local and national regulatory requirements. These contributions will help the PACE provide unique insights into the risk and pathophysiology of OUD and the identification and development of more efficacious treatments for pain and OUD.